Paper making method and machine



H. A. CHUSE PAPER MAKING METHOD AND MACHINE Filed Oct. 6, 1934 5Sheets-Sheet 1 a n a .o- .HQ. 0 G w o M kw o 1 u Ma N Aug. 31, 1937. H.A. CHUSE 2,091,805 PAPER MAKING METHOD AND MACHINE I Filed Oct. 6, 19345 Sheets-Sheet 2 for i W i W5 7 M W.

Q N x E QM Aug. 31, 1937.

H. A. CHUSE PAPER MAKING METHOD AND MACHINE Filed Oct. 6, 1954 5Sheets-Sheet 3 NWE M e JMLL Aug. 31, 1937. H. A. 'CHUSE PAPER MAKINGMETHOD AND MACHINE Filed 001;. 6, 1934 5, Sheets-Sheet, 4

5 Sheets-sheet 5 H. A. CHUSE PAPER MAKING METHOD AND MACHINE Filed Oct.6, 1934 OOOOOOOOGG Jid/ iv 2 v 7 0 7a? 7. (we: MM )au w? mmN Aug. 31,1937.

. WMN MMN NWN Patented Aug. 31, 1937 UNITED STATES PATENT OFFICEApplication October 6,

9 Claims.

This invention, relating to paper making methods and machines, isconcerned particularly with the procedure and equipment employedsubsequent to the making of the wet sheet; the objects of the inventionbeing to provide an improved method and means for drying paper in theprocess of manufacture in a'continuous'sheet, and to provide an improvedmethod and means for the entire procedure to which the paper sheet issubjected after its removal from the medium on which it is formed. In ageneral sense the invention may be regarded as providing a novel papermaking method and machine as a whole, though not involving novelty withrespect to the making of the wet sheet.

The process of making paper in a continuous sheet involves progressiveremoval of water from the formed sheet by the action of a succession ofagencies. On a Fourdrinier paper-making machine, for example, theremoval of water from the paper sheet begins while the sheet is still onthe making wire, much water being removed by draining through the wire,some water being displaced from the sheet by the action of the flatsuction boxes across which the wire slides, and an additional percentageofwater being forced from the sheet-by the action of the suction couchroll at the delivery end of the wire. However, after the sheet. hasformed with accompanying drain- 30 age of its surplus water by gravityand table roll action, the water contained in the sheet is sotenaciously held that only a limited reduction of the water content ofthe sheet can be accomplished by the action of the flat suction boxesand the suction couch rell. Ordinarily when the wet sheet leaves themaking wire, or after it has passed the suction couch roll, it will beonly about or less dry, or in other words will contain 80% or more ofwater, depending upon the thickness or the sheet, the stock from whichit is formed, the speed at which it is made and the efiiciency of theflat suction boxes and suction couch roll to reduce the moisture contentof the particular sheet made at the particular speed.

Thus the wet paper sheet delivered from a Fourdrinier making wire orother medium on which the sheet is formed is composed of a relativelylarge proportion of water and a relatively small proportion of papermaterial, by weight,

the percentage of water contained in the sheet being, as above stated,ordinarily about 80% or more. This great amount of water or most of itmust be removed from the sheet by subsequent r operations to reduce thesheet to the relatively low moisture content desired for the calendering1934, Serial No. 747,175

ing wire or medium on which it is formed and the calendaring operation,the conventional method which for many years has been and is nowemployed involves the expressing or squeezing out of a certainproportion of the water from the wet sheet by the action of a series ofpresses,

which requires the carrying of the wet sheet on moisture absorbing pressfelts through the first and second presses and sometimes through thethird press; and the drying of the sheet after pressing by carrying thesheet around or in contact with a series of ordinary driers consisting iof revolving steam heated cylinders which heat the paper and cause itsdrying by evaporation, the evaporated moisture being carried oil. byventilation.

As the paper cannot be produced any faster than it can be delivered insufficiently dry state for the calendering operation, the capacity ofordinary drying equipment required for a paper making machine willdepend upon the speed at which the paper made on such machine is formedand delivered to the driers, and upon the amount of water contained inthe sheet when it is delivered to the driers, wherefore it has beenconsidered advisable to remove by pressing or by pressing andsupplemental agencies as much water as it is practicable to remove fromthe sheet in this manner before the sheet is delivered to the driers.The modern high speed Fourdrinier paper making machine of conventionalcharacter has therefore elaborate press and press felt equipment, andextensive drying equipment to provide the drying capacity required fordrying the paper as fast as it is delivered from the Fourdrinier makingwire or other medium on which the sheet is formed.

Now the press section of a paper making machine, besides comprisingelaborate and cumbersome equipment occupying a considerable amount ofspace, has always been and is a troublesome part of the machinery, dueamong other causes to the difficulty of running the paper through thepresses without breakage or without injuring the paper or by crushingeffects. The speed at which paper can be produced on conventionalmachines is primarily limited not only by the rate at which it can beformed on the table but also by the speed at which it can be run throughthe presses without injury and then dried for calendering. Modernimprovements in the Fourdrinier including particularly the slictioncouch roll, and the use of long press felts of good quality and otherimprovements in connection with the presses including particularlysuction press rolls, have made it possible to pro duce ordinary newsprint paper at speeds ranging up to 1,000 ft. per minute and over.Nevertheless the press section of the Fourdrinier remains a troublesomefactor and is believed to impose a speed limitation without which itmight be possible in the future to attain substantially higher speeds inpaper production than are now feasible.

Moreover the press section of the paper machine requires constantattention, the maintenance of the press felts in cleansed condition, andthe frequent removal and replacement of press felts, with consequentexpense. Furthermore the amount of water which can be removed from thesheet by pressing, or by the use of a series of heavy presses inconjunction with press felts, is quite limited. Ordinarily the sheetafter it leaves the third or last press of the paper making machine willcontain about 65% or more of water, which large amount of water exceptthe low percentage desired to be retained in the finished product mustbe removed by drying, requiring consequent extensive drying equipmentwhere the conventional method of drying is employed.

The present invention contemplates a radical departure from conventionalpaper making methods and machines with respect'both to the drying anddrying equipment in the ordinary sense and the entire procedure betweenthe stages of delivery of the wet sheet from the-Fourdrinier making wireor other medium on which it is formed and the calendering of the sheet.The invention provides for drying the sheet in such manner as not onlyto give requisite drying capacity for a high speed paper making machinewith much less extensive equipment than if ordinary driers were used,but also in such manner as to dry the sheet advantageously andeconomically without preliminarily removing water from the sheet bypressing, and yet with substantially less extensive equipment than theordinary drying equipment required after the sheet has been subjectedtothe usual pressing operation. Thus the invention contemplates omissionof the step of removing water fromthe sheet by pressing,

thereby'eliminating the elaborate, cumbersome and costly press and pressfelt equipment with all of its diificulties and objections. On the otherhand, pressing the. sheet while sufiiciently moist to be'compacted andsmoothed by the pressing is desirable, and the invention contemplatesretaining a limited pressing operation preferably performed by a singlepair of press rollsoperating on the bare paper sheet at a stage of thedrying operation after the sheet is too dry for expressing moisture offor injury by the pressing operation. Preferably the pressing is donewhen the sheet is about from 70 to 80% dry, or in other words when themoisture content of the sheet is reduced tofrom about 20% to 30%, ithaving been fiber strength to conduct the pressing'operation when thesheet has been reduced'to such a rela-- the drying of the paperprincipally or mainly found most advantageous from the standpoint of,

- next suction drier.

before pressing, and the reduction of the pressing operation to acompacting and smoothing operation at an intermediate stage in thedrying operation, preferably by the use of a single press,

after the sheet is of too low a moisture content of the invention inconnection with the said drying methods and equipment, are susceptibleof general utility in the paper making industry, or in other words thatthe drying methods and equipment embodying the present invention orfeatures thereof are intended to replace present methods of drying inpaper manufacture, whether with or without preliminary removal of waterfrom the paper sheet by pressing or by pressing and other agenciesbefore delivery of the sheet to said drying equipment.

For the paper drying process, the invention utilizes extensively theproperty of air to absorb moisture with which it is brought intointimate contact. According to the invention, the drying processinvolves successively forcing large volumes of air through the papersheet, under conditions promoting vaporization of the moisture in thesheet and the absorption and carrying off of the moisture by the airpassing therethrough. In carrying out the invention the paper sheetdelivered from the making wire may be entrained about a series ofrevolving closely perforated cylinders, the air being forced through thepaper and the perforations in the cylinders. The forcing of the airthrough the paper may be induced by external air pressure or by suctionwithin the cylinders or by a combination of both. As the most expedientand practicable system, suction within the cylinders is employed. Thesaid cylinders may consist of the perforated shells of suction rolls ofappropriate construction to provide extensive suction areas to be sealedby the paper sheet entrained about the cylinders. For convenience suchcylinders are herein referred to as suction driers to distinguish fromthe ordinary driers which merely heat the paper sheet to causeevaporation of moisture.

The process of drying the paper by forcing air therethrough can behastened and can be ac complished with a smaller use of air than wouldotherwise be needed by heating the air considerably and heating thepaper sheet occasionally or in alternation with the forcing of theheated air therethrough. The process of evaporation by air circulatingin intimate contact with the moisture in the sheet has a cooling effectnotwithstanding that the air forced through the sheet is in a heatedstate. It is therefore highly advantageous to heat the paper sheetoccasionally or in alternation with the serving proper heat balance forfull rnoisture saturation of the heated air passing through the sheet.It will be understood that the volume of heated air which passes throughthe paper sheet on any suction drier absorbs and carries oif a certainproportion of moisture/in the sheet, but with a cooling effect as abovenoted, which without. succeeding heating of the sheet would reduce themoisture absorbing effect of the volume of heated air passed through thesheet on the By carrying the sheet around ordinary driers in alternationwith the suction driers, the desired heat balance between the sheet andthe heated air to be forced therethrough is restored. The heat impartedto the sheet by the ordinary driers promotes rapid vaporization of themoisture in the sheet and full moisture saturation of the airsuccessively passed through the sheet.

On ordinary paper machines the ideal temperature of the paper is fromfive to ten degrees below the temperature of the steam heated driers,and it remains constant. By a system of drying the paper by carrying italternately around ordinary driers and suction driers, the

paper leaves a. heated drier at about the same temperature as inordinary practice but under the evaporation process in the succeedingsuction drier or driers it may cool 100 or more by the time it reachesthe next reheating drier;

hence the average temperature range will produce a flow of heat from theheated drier to the paper of five or six times the rate possible withthe old method.

With ordinary methods of drying, there is considerable diificulty indrying the paper to the narrow limit desired by the trade. If the papercontains too much moisture it will not print well.

If delivered too dry, there is a loss in desired weight and thecalendering is not so effective 0 nor will the paper print as easily asif properly calendered. The invention contemplates therefore drying thepaper to a higher degree than is desired for calendering, and thenconditioning the paper for calendering by forcing moisture laden airthrough the paper just before it is calendered.

Other method and mechanical features of the invention will be apparentfrom the following description of certain methods and machines embodyingthe invention, reference being had to the accompanying drawings inwhich:

Fig. 1 is a diagrammatic view of a paper making machine of onepracticable construction embodying and for practicing a method embodying5 the invention.

Fig. 2 is an enlarged view of the first section of the drying equipmentof said machine.

Fig. 3 is an enlarged view of the second section of said dryingequipment.

tion of said drying equipment.

Fig. 5 is a crosssection through one of the drying sections andcondensing apparatus as sociated therewith.

Fig. 6 is a diagrammatic view of a modified machine embodying featuresof the invention.

Fig. 7 is an enlarged view of the second section (Faii thg dryingequipment of the machine shown in Fig. 9 is a view partly in endelevation and. partly in cross section of said suction drier.

Fig. 10 is an end view of blocking oif means of a suction drier.

Fig. 11 is an enlarged detail view of the blocking ofi means shown inFig. 9.

The specific machine selected for illustration will now be particularlydescribed, it being understood that the following description thereof isto be taken asexplanatory and not as limiting the. invention which ishereinafter set forth in the claims.

In Fig. 1, the reference numeral l designates the making wire of a highspeed Fourdrinier paper making machine. The wet section 'of the ma- Fig.4 is an enlarged view of'the third sec- Fig. 8 is a longitudinal sectionof a suction drierchine, represented by the making wire, will beunderstood as including all approved equipment necessary or desirable inconnection with the making of the wet sheet, including liquid stocksupplying apparatus, the breast roll, table rolls, deckles, dandy roll,fiat suction boxes and other accessories employed in modern high speedFourdriniers. The making wire at its delivery end is entrained on asuction couch roll 2 whereby the wet paper sheet which forms on themaking wire, after submission to the action of the flat suction boxes,is subjected over the suction couch roll to a constant high tensionvacuum action with a resultant consolidating and moisture reducingefiect such that the paper sheet is made in a relative firm and intactcondition, though containing, as before indicated, usually about percent or more of water. The wet sheet made on the machine is designatedby the numeral 3.

The machine represented in Fig. 1 comprises the Fourdrinier wet section,herein represented by the making wire, drying equipment which in thisinstance is in three sections, a single press 4 located between thesecond and third sections of the drying equipment, andcalenders 5; therebeing no press section in the ordinary sense of equipment for pressingwater from the paper sheet preparatory to drying.

The drying equipment, shown more clearly in Figs. 2, 3, and 4, comprisesin this instance a series of driers numbered 6 to 29, inclusive,including suction driers numbered 1, 9, ll, I3, l5, l1, [9, 2|, 23, 24,26, 27, 28, and ordinary driers numbered 6, 8, l0, l2, l4, l6, i8, 20,22, 25. sheet is carried successively around the driers in the order inwhich they are numbered. With the particular arrangement shown, thepaper sheetis carried alternately around suction and ordinary driers inthe first and *second sections of the drier equipment (Figs. 2 and 3),and in the third section is carried alternately around ordinary andsuction driers and then, around a succession of suction driers 26, 21,2B and then around a conditioning unit 29 which is similar to thesuction driers but is employed in this instance for forcing moistureladen air to the dry paper sheet preparatory to calendaring.

Each suction drier comprises a revolving cylinder in the form of aclosely perforated metal shell 30 having closed ends and containingalarge perforated suction pipe 3| in connection with suitable vacuumpumping apparatus (not shown) The paper whereby to maintain sufflcientsuction or vacuum action within the cylinder to cause the forcing of airfrom the exterior of .thepylinder through the paper sheet entrainedthereon. The major portion of the cylindric area of such suction drieris sealed or covered by the paper sheet passing around or about thedrier, while the small segment which is not covered by the paper sheetis blocked on by means indicated atv 32 in Figs. 2 to 4 to prevent theingress of air through the perforated area not covered by the sheet,whereby to cause all air drawn into the cylinder topass through thepaper. Each cylinder may be covered or jacketed by a wire cloth jacket33 (Figs. 8 and.9) to avoid any possibility of water marking or othermarking of the sheet by the perforated pattern of the shell.

As before stated, the drying system in th illustrated machine isarranged in three sections respectively shown in Figs. 2, 3, and 4. Eachdrying section comprises a number of said suction driers and-of saidordinary driers, together with suitable carrying means for carrying thepaper sheet successively around the driers or with carrying and holdingmeans for-carrying the sheet around certain of the driers and forholding them in cooperative relation with certain of the other driers,which carrying means or carrying and holding means are represented bythe drier felts'hereinafter referred to, though in some instances andparticularly in the manufacture of paper heavier and denser thanordinary newsprint the drier felts or certain of them may be replaced bywire cloth aprons.

nection with a source of warm or preheated air, and contain air dryingor air heating equipment, such for example as steam heating coils. Allsteam heating coils in the several drier sections are designated by thenumeral 34.

The first drier section (Fig. 2) which receives the wet paper sheet fromthe Fourdrinier making wire, and in which the most elementary stage ofthe drying is performed, comprises the ordinary driers 6, 8, l0, l2 andsuction driers T, 9, ll, I3 arranged in alternation therewith, and thecoacting felts 35 and 3B which receive the paper sheet between them andcarry the sheet successively substantially surrounding the respectiveareas of the suction driers which are entrained by the felts and papersheet carried thereby. As shown,

the wet paper sheet 3 delivered from the Fourdrinier making wire. isdeposited upon the felt 35 which carries the sheet through the guideopening 42 into the housing and travels around the guide roll 38 wherebythe sheet is brought into contactwith the coacting-felt 36 and the twofelts carrying the sheetbetween them travel successively around thedriers. The sheet passes from the last drier l3 under the guide roll 43and out from the housing for delivery to the next section of the dryingequipment. In the particular construction shown in Fig. 2, the housingopening through which the paper sheet emerges is substantially closed bythe drier-I3 and guide roll 43. Guide openings in the housing for thereturn run of the lowerfelt 3? are indicated at 4%.

With the illustrative arrangement of the felts 35 and 35 of the firstdrier section, one of said felts is inside the paper and the other feltis outside as the paper is carried around the driers. This arrangementis advantageous for the first stage of the drying paper sheet in therelatively wet condition in which it is received from the Fourdriniermaking wire. It protects the freshly made wet paper sheet from thesudden heat of thefirst driers, thus protecting the sheet from tendencyto burn to the driers. It passes the paper sheet from drier to drier,will deliver all broke for removal as hereinafter described, and

The driers of. each section are enclosed by a housing in cona driersection, whereby the moisture content of the sheet is reduced below thatobtainable by use of the ordinary elaborate press and press feltequipment, so that the sheet delivered from said first drier sectionwill be substantially dryer than when delivered to the drying equipmentof a paper making machine having conventional press and drier equipment.

The -.second drier section (Fig. 3) comprises the suction driers l5, l1,l9, 2| and ordinary driers I4, I6, [8, arranged in alternation with saidsuction driers, a felt 45 which travels successively around all of thedriers, and a felt 46 which cooperates with the suction driers to assistin passing the paper sheet and in holding the sheet to said suctiondriers, said felt 46 being arranged for short are contact with the sheeton said suction driers. The housing for the second drier section isdesignated by the numeral 41, and the warm air inlet by the numeral 48.Guide openings forthe felt 45 are indicated at 49. Guide rolls at thepaper inlet and outlet ends of the drier are indicated at 50 and 5|;other guide rolls for the felts at 52, and adjustable take-up rolls fortensioning the felts at 53. Within the drier housing 41 are steam coils34 arranged in association with the suction driers in the same manner asalready described. g

The paper sheet delivered from the first drier section is deposited uponthe felt 45 and follows the same route as said felt throughthe seconddrier section, passing with the felt into the drier housing 41 and overthe guide roll 50 and then successively around all the driers and thenpassing with said felt under the guide roll 5| and out from the drierhousing.

With the arrangement of 'felts employed in the second drier section, thepaper sheet passing through said section is inside the felt 45 as itgoes around the ordinary driers l4, Hi, It, 20,

so that the paper sheet is carried in direct contact with said ordinarydriers or steam heated cylinders as is now desirable for efiicientheating ,of and rapid evaporation of moisture from the partly driedsheet. On the suction driers l5, l1, I9, the felt 45 is on the inside ofthe paper sheet as before to protect the paper. The small contact of theother felt 46 presents less obstruction for the passage of air throughthe paper sheet than does the ordinary arrangement.

As the sheet is delivered to the second drier section in a partiallydried state and without having undergone the compressive action ofpresses, the forcing of heated air through the sheet is very effectivein the second drier section, and by this action in alternation with theheating ,of the sheet on steam heated drying cylinders or ordinarydriers the sheet in passing through said second section is further driedin an advantageous manner, and may-be rendered as dry as or dryer thanafter having passed through threefourths of ordinary drying equipment.

In both the first and second drier sections,

the feltsmust have a very beneficial effect in moisture and surrenderingit to the warm air through which the felts are continually passing. Thisfeature is especially strong in the first drier section. The two feltscan hardly fail to reach the paper except-in dry and hot condition.These two dry and hot felts pressed one on each side of the wet sheet ofpaper will instantly take up a large percentage of its moisture whichwill be removed from the felts by evaporation on the return runs of thefelts.

The function 'of the first and second drier sections is to dry the papersufficiently to bring it to an advantageous state of dryness forpressing. As before indicated, it is desirable to avoid pressing whilethe paper sheet is relatively wet, and to press the paper for compactingand smoothing effect after its moisture content has been reduced to fromabout 30% to almost 20%. Probably the most advantageous moisture contentof the paper sheet for pressing is about or near to 20%. It iscontemplated therefore that the capacity of the first and second driersectionsshall be such that the paper sheet delivered from theseconddrier shall be between 70% and 80% dry, preferably about or near80% dry. After delivery from the second drier section, the paper sheetruns through the single press 4 for compacting and smoothing, and isthen delivered to the third drier section for further drying preparatoryto calendering.

The third drier section comprises the ordinary driers 22 and 25, suctiondriers 23 and 24 in alternation therewith, additional suction driers 26,27, 28 and conditioning unit 29, a felt 54 arranged to cooperate withthe lower tier of driers Z2, 24, 2B, 28, and'a short felt 55 arranged tocooperate with the one ordinary drier 25 of the upper tier of driers.The felt 54 is held in cooperative relation to the lower tier of driersby the guide rolls 56, while the return run of said felt is engaged byguide rolls and the adjustable take-up roll 58 for tensioning the felt.Guide rolls for the short felt 54 are indicated at 59.

The housing for the third drier section is num- Some of the steam coilsin the housing 60 are also arranged in proximity to the surfaces of theordinary driers 22 and 25 which are engaged by the paper sheet andfelts.

In the third drier section the paper sheet is covered by the felt 54 onthe ordinary drier,22 and by'the short felt 55 on the ordinary drier 25,but is carried around the suction driers free of felts except for theshort contacts of the felt 54' on the suction driers 24, 26, 28. As thepaper sheet passes through the third drier section, the drying of thesheet is continued, first by the alternate action of ordinary driers andsuction driers, and then by the continued forcing of heated air throughthe sheet on the suction driers 26, 21, 28, whereby the paper sheet isrendered sufiiciently dry for calendering or, in this instance, dryerthan desired for calendering.

Because of the difficulty of drying paper to the narrow limits desiredby the paper trade, the illustrative machine is designed to dry thepaper continuously too dry and then to condition the Within the drierhousing 60 are" paper for calendering by passing moisture laden airthrough the sheet, utilizing for this purpose the roll 29 which issimilar to the suction driers. As shown in Fig. 4, the conditioning unit29 is contained in a separate compartment of the drier housing, whichseparate compartment is formed by the partition 64. Warm moist airenters said compartment through the inlet openings 65 and is drawnthrough the paper sheet on the unit 29, conditioning the paper forcalendering. Water coils 66 may be arranged in said compartment forcooling the warm moist air entering the same .to a predeterminedtemperature which may be kept constant by a suitable temperature control(not shown) which admits just enough cooling water to do this. The airhaving a constant temperature will have a constant ca-* pacity formoisture as any excess of moisture in the entering air will be condensedand carried out by the drip collector 61. Since paper has a greataffinity for moisture if subjected to moisture laden air, it will drawmoisture from the saturated air which is passed through it. Thisabsorption will depend upon the relative humidity of the air, keptconstant as above indicated, and the time of exposure. The time ofexposure is kept constant as it is the time required for the paper topass overthe suction unit 29. Hence, paper at or near. the desired finalmoisture. content will be tempered to very close limits by properlygoverning the temperature of the saturated air passed through it. Theamount of absorption of moist air by the paper could also be controlledin otherways as for example by the method hereinafter explained withreference to Figs. 6' and 7.

In threading the paper sheet through the drying apparatus, the sheet iscarried through the first drier section by the coacting belts 35 and 36.It may be threaded through the second drier section by means of anordinary Shehan carrier (not shown). However it is possible to threadthe paper sheet through the second section by means of the felt 45 withthe assistance of air jets presently to be referred to and with theassistance of the top felt 46. For threading the other suitable sourcefrom a series of pipes 68 located within said suction drier. The brokensheet may be caught on the broke catcher 69 and discharged through anopening normally closed by the door 10. In, the second drier section(Fig. 3), a number of air nozzles H are arranged to discharge jets ofair against the sheet in directions to hold it against the suctiondriers as the sheet passes thereto from the ordinary driers. Hence anybroke will be carried around an ordinary drier by the felt 45, andthence to the next suction drier by the said felt withthe assistance ofthe air jets discharged at H, and over said suction drier by the topfelt 46 cooperating with the lower felt; and after the broken sheetpasses from the felt 46 the suction within the suction drier will causethe sheet to hug to the felt .45 and be carried thereby to the nextordinary drier. Thus broke will be delivered in the second drier sectionto the last drier 2|, from which it may be blown off by air blowing frompipes '12. The broken sheet may be caught on the broke catcher I3 anddis- 5 charged through an opening normally closed by the door 14. In thethird drier section, nozzles are arranged to discharge jets of airtoward the receiving sides of the several suction driers. Additionalnozzles I6 near the off-bearing side of the drier 22 are arranged todischarge air downwardly. The several suction driers are provided withair pipes H for blowing the paper sheet from the ofi-bearing sides ofsaid driers. The suction driers 24, 26, 28 in the lower tier of driersare provided with additional air pipes 18 arranged to blow air from thereceiving sides of said driers. If a break occurs on the first drier 22,the broke will be blown from the ofi-bearing side of said drier by thenozzles and will be car- 20 ried' by the felt 54 under the lower tier ofdriers, the air discharged by the pipes 18 preventing the broke fromascending the receiving side of any of the driers 24, 26, 28. If thebreak occurs on the suction drier 23, the air jets discharged by thenozzles 15 associated with this drier will hold the sheet to itsreceiving side and the suction within the drier will hold it to itsoff-bearing side, and the broke will be blown off by the air blowingfrom pipes 11 in said drier and will be held to the next drier 24 by theair jets discharged from nozzles 15 associated therewith. Thus the brokewill be caught on the felt 54, and will be prevented from ascending thereceiving 3? side of any of the suction driers 24, 26, 28 by thedischarge of air from pipes 18. 'If'broke occurs at any subsequent stagein the third drier section, the mode of handling it will be obvious.Nozzles I9 near the off-bearing side of the drier 28 are arranged todischarge air downwardly to 40 assist in discharging broke over theslide 80 iglgirough an opening normally closed by the door The blow-offpipes 68 in the last drier of the first drier section, the correspondingblow-off pipes 12 in the last drier of I the second section, the nozzlesll of said second section, the nozzles l5, l6 and 15 of the thirdsection, and the blowoff pipes TE and 18 of the suction driers of saidlast section, are used respectively only to assist 0 in carrying thesheet when it is being threaded through the machine, or to carry broke.These several nozzles and blow-off pipes may be connected throughseparate valve-controlled connections (not shown) with any suitablesource of compressed air, so that the air can be turned on for use whenand if required, and shut off during the normal use of the machine.

The sheet metal-casings or housings containing the drier sections areconstructed with numerous doors to permit access to the driers, feltsand paper. As shown in Figs. 2 to 4, the drier housings are constructedwith various doors or hinge sections in the top, ends and bottom.Various other doors or hinge sections are provided in the .sides of thehousings.

It is desirable to provide for recovery and utilization of the largeamount of heat that is contained in'the air and moisture discharged fromthe various suction driers, and particularly from those of the firstdrier section which removes from the wet paper sheet by evaporationwater that is ordinarily pressed out and which uses a relatively largeamount of heat. Reference will now be made. to provision for such hea IQOV 'Y- As shown in Fig. 5, the suction driers of the first driersection are connected to vacuum-pumping apparatus (not shown) through acounterfiow heat intercharger comprising a casing 82 having inlet andoutlet chambers 83 and 84 connected by a series of condenser tubes 85.The inlet chamber 83 is connected by the piping 86 with the suctionpipes in the suction driers, and the outlet chamber 84 is connected bythe pipe 81 with the vacuum-pumping apparatus. The tubes extend. throughan intermediate chamber 88 through which is drawn the air that issupplied to the first drier section. The air to be so supplied is drawnfrom the fresh air duct 89 and discharges through the outlet duct 90either direct to the housing of the first drier section or to anintermediate apparatus for further pre-heating the air. The fresh airthus drawn through the heat intercharger condenses about 90% of themoisture in the air discharged from the suction driers, thus heatingsuch air and recovering a large amount of heat that. would otherwise bewasted} while the moisture condensed in the tubes 85 may be drawn offthrough the hot water outlet 9| and may be used again as hot as desiredin the white water supplied for making the pulp solution to be used onthe wet section of the machine or may be used as boiler feed water.

Each section of the drier may be equipped with similar heat recoveryapparatus, or the entire series of suction driers may be connected withsimilar apparatus of sufficiently large capacity to recover the heat inthe air and moisture discharged from all the suction driers.

The air supplied to the drier sections is thus preheated by the heatdischarged from said sections, with accompanying condensation of thewater discharged from said sections. The condensed hot water can be usedas boiler feed water. white water or for heating .purposes. Thus theactual consumption of heat in the drying process is materially reduced".The preheated air supplied to the drier sections may be furtherpreheated by passing over steam coils supplied with exhaust steam fromthe engine or bleeder turbine. In the drier sections the air is furtherkcheated by steam coils 34, in which some. live steam may advantageouslybe used, though it is intended to use principally exhaust steam in thecoils 34 as well as in the ordinary driers or steam heated dryingcylinders.

The hot moist air supplied to the conditioning unit 29 may be derivedfrom any suitable source; for example the suction pipe of an individualsuction drier in the first drier section may be connected with theinlets 65 01 the chamber in which the conditioning unit 29 is situated,so that the conditioning unit will draw the. supply of moist air fromsuch drier.

The drying equipment described with reference to Figs. 1 to 5 is inaccordance with a construction and arrangement of drying equipment whichhas been designed for a machine for high speed production ofnewsprintpaper. It will be understood that said equipment may bevariously modified as to the number of drying sections, the number andarrangement of suction driers and ordinary driers in the respectivesections, and as to various details, to suit various differentconditions and requirements. It is contemplated for example that wiresmay be used in place of some or all of the felts, that some of the feltsmay be omitted, or others added, and that drying systems embodyingfeatures of the invention may omit all felts or wires for carrying orholding the paper sheet.

The wet section of .the illustrative machine represented by' theFourdrinier making wire I typifies any suitable wet section. The wire Itypifies any suitable medium on which the wet paper sheet is formed orany suitable carrying medium to which the sheet is transferred from thesurface on which it is formed.

Reference will now be made to Figs. 6 and 7, which represent a machineembodying features of the invention and adapted for conditions in whichthe sheet of paper or paper material can be dried for pressing with lessdrying capacity than that of the machine first described. The machine ofFigs. 6 and '7 is in accordance with a con struction designed especiallyfor manufacture of bulky or loose paper such as blotter and the like. Itwould also be suitable for drying pulp sheets if the press were omitted.

The wet section of the machine shown in Figs. 6 and '7 is represented bya Fourdrinier making wire I 00 entrained at its delivery end on asuction couch roll I M tions I02 and I03, a press I04 between the twodrier sections, and calenders I05.

The first drier section I02 comprises a series of suction driers I06 andcooperating felts or wires I01 and I08 by and between which the papersheet I09 is carried successively around said suc-' tion driers. Saiddrier section is enclosed by a housing similar to the housing previouslydescribed, and contains steam heating coils IIO.

The sheet in passing through said section is dried 30 by the forcing ofthe heated air through the sheet,

'together with the drying effected by the hot felts and the heatradiated to the sheet from the heating coils.

The second drier section I03 comprises ordinary 4O driers I I I, suctiondriers I I2, a felt I I3 which cooperates with the lower tier of driers,and a short top felt II4 cooperating with the one ordinary drier in theupper tier. This second drier section is substantially similar in allrespects to the last drier section of the machine shown in Fig. 1,except that in the machine of Figs. 6 and 7 a different means isprovided for conditioning the sheet for calendering. In the machine ofFigs. 6 and 7, the paper sheet passes successively around the driers andfrom the last drier passes around guide rolls H5 and H6. Moist air forconditioning the sheet is drawn through the sheet on a segment of thelast suction drier. The moist air is drawn from a suitable source ofsupply into the inlet chamber Ill and flows from said chamber throughthe passage II8 to the hood II9 from which the moist air is drawnthrough the sheet by the suction in the last suction drier. The passageH8 is controlled by the rotary valve I20 operated by the lever arm I 2i.The lever arm HI is pivotally connected to and suspended from link I23,the last mentioned link being pivoted to the drier housingat I24. LinkI22 is pivotally connected to the long arm I25 of a bell crank leverwhichis fulcrumed at I26 and the short arm I21 of which carries anadjustably mounted weight I28. Another weight I29 is adjustably mountedon the arm I25 of the bell crank lever. The arm I25 of the bell cranklever carriesa roller 30 held against the paper sheet between the guiderollers H5 and H6. The weights I28 and I29 are so adjusted that theroller I30 bears against the paper sheet. When the paper sheet taut theparts are in the position shown in Fig. 7, the valve I20 being open. Ifthe paper The machine has two drier secsheet receives too much moisture,the sheet will stretch between the rollers H5 and H6, allowing theroller to move toward the right and close or partially close the rotaryvalve I 20, thereby regulating the amountv of moist air that can bedrawn through the sheet from the hood II9.

Reference will now be made to Figs. 8 and.9, illustrating onepracticable construction for a suction drier. As before stated, thereference numeral 30 designates the perforated shell of the drier, 3|the perforated suction pipe therein, 32 the means for blocking off thesegment of the shell which is not sealed by the paper sheet, and 33 thewire cloth jacket on the sheet.

In the specific construction shown, the shell 30 is rigidly attached toheads I3I and I32. The suction pipe I3I has at one end a tubularextension I33 extending through the head I3I and secured in the hearingor support. I34. The head I3I is rotatably mounted on the extension I33by the bearing I35. The suction pipe communicates with thevacuum-pumping apparatus (not shown) through the passage I36 in thesupport I34 registering with an opening in the suction pipe extensionI33 which is closed at its outer end. At its opposite end the suctionpipe has a projecting trunnion I3'I on which the head I32 is rotatablymounted through the bearing I38. Said head I32 has an extended journalportion I39 journalled on the fixed bearing I40.

As shown in Fig. 9, the suction pipe 3| is constructed with a projectingmember of T-shaped cross section comprising the radial web MI andsegmental web I42 connected with the end sectorshaped webs I43 andtn'aced'by intermediate sector-shaped webs I44. Attached to thesegmental web I42 are side members I45 and segmental end members I46which are preferably very nearly but not in actual bearing contact withthe interior of the perforated shell 30. The construc tion referred toincluding especially the web I 42 carried by the suction pipe and theside members I45 and end members I 40 attached thereto constitute theblocking ofi means which has been referred to as a whole by the numeral32.

It is desirable to avoid rubbing contact between the blocking off meansand the interior surfaces of the revolving perforated shell, since therewould be no adequate means of lubricating these surfaces if in rubbingcontact. Hence it is desirable to'maintain a slight clearance of from.001" to .003? between the interior surface of the shell and theadjacent surfaces of the members I45 and I 46. The members I 45 areattached to the flanged or enlarged sides of the segmental web I42 bybolts I41 passing through short slots in said members. Adjusting screwsI48 passing through the extensions I49 of the flanged sides of the webI42 bear against the members I 45. By adjusting the screws I48 themembers I45 may be moved as closely as desired to the inner surface ofthe rotating shell, and the screws I41 may then be tightened to fastensaid members in place. The screws I48 are provided with lock nuts I50.Theend members I46 are adjustably secured to the ends of the web I42 byfastening screws I5I passing through short radial slots in said members.

In making newsprint paper, and various other papers having considerableporosity, large volumes of air can be drawn through the paper sheet onthe suction driers With the use of a comparatively low vacuum, so thatthe leakage of air which will take place through the very slightclearances between the members I45, I46 and incomposition or be providedwith packing strips of special metal or composition to reduce thefriction.

Within the suction pipe 3| are pipes I52 and H53 connected throughvalve-controlled connections (not shown) with any suitable source ofcompressed air, andfrom which respectively extend the blow-01f pipes I54and I55. The blow- .oif pipes I54 correspond to the blow-off pipes IT inFig. 4, and the blow-off pipes I55 correspond to the pipes-B8 in Fig. 3and I8 in Fig. 4. 1

All of the suction driers may be of the construction described or othersuitable construction. The illustrative construction of the suctiondrier is included as a feature of this invention, but the invention inother aspects is not limited to any specific construction of the suctiondrier.

Besides eliminating ordinary press and press felt equipment and all theobjections incident thereto, the present invention makes possible a verysubstantial reduction in drying equipment, as compared with ordinarydrying equipment, thus reducing the investment required for machinery,machinery space and buildings and also materially reducing maintenanceexpense. The majority of the steam traps and about threefourths of thedrier steam joints and siphons required in connection with ordinarydrying equipment can be eliminated by the use of the present invention.The paper can be made stronger and of better quality and in greatervarieties than by ordinary methods. By controlling the humidity of thepaper for calendering, the paper will ar-.

rive at the calenders at a more constant condition and will calenderwith a more uniform finish.

By using heat'over and over again in the drying apparatus a substantialeconomy is effected. Due to the heat recovery system, a saving -in thepower required to produce suction in the suction driers is effected byreason of the condensation of the vapor in the discharged air. Therecovery of pure hot water for use over again as white water is highlyadvantageous, avoiding low temperature which tends to congeal the sizingin the paper when made on a Fourdrinier having ordinary press and drierequipment. As there is no escape of'hot vapor into the machine room, theworking conditions are much improved for the machine crew. The samecondition prevents the condensation of moisture on the ceiling, overheadpipes and the like, and the dripping of dew on the finished paper,thereby preventing damage.

Whatl claim as my invention, and desire to secure by Letters Patert, is:

1. A paper making machine comprising a wet section on which the papersheet is made in the wet state, drying equipment to which the wet sheetis delivered from said wet section, said drying equipment comprising aseries of drying rolls around which the sheet is carried, certain ofsaid rolls being perforated suction drying rolls having associated meansfor continuously forcing heated air through substantially the entirearea of the sheet entrained on said perforated rolls and the other rollsbeing heated drying rolls, a press throughv which the sheet passes afterdeliveryfrom said drying equipment, and further terior of the shell willnot be serious, and all drying equipment through which the sheet passesafter pressing.

2. In paper drying apparatus, a series of driers comprising ordinarydriers and suction driers, a housing containing the same, said housinghaving awarm air inlet, steam coils in said housing for heating the airtherein, said coils being arranged in proximity to the suction driers,and coacting felts'for carrying the paper sheet successivelyaround saiddriers.

3. The improvement in the process of making paper in a continuous sheetwhich comprises partially drying the sheet before any pressing by dryingaction involving the carrying of the wet sheet between heated felts andsuccessively forcing large volumes of heated air through the sheet, andthereafter drying the sheet by heating it and successively forcing largevolumes of heated air therethrough.

4. The improvement in the process of making paper in a continuous sheetwhich comprises partially drying the sheet before any pressing by dryingaction which involves carrying the sheet between heated felts whilesuccessively forcing large volumes of heated air therethrough, furtherdrying the sheet before any pressing by heating it and successivelyforcing large volumes of heated air therethrough, and thereafter dryingthe sheet by heating it and successively forcing large volumes of heatedair therethrough.

5. The improvement in the process of making paper in a continuous sheetwhich comprises partially drying the sheet before any pressing bycarrying the sheet between heated felts while alternately heating andforcing large volumes of heated air through the felts and interposedpaper sheet, further drying the sheet before any pressing by alternatelyheating the sheet and forcing large volumes of heated air therethrough,and thereafter drying the sheet by drying actioninvolving successivelyforcing large volumes of heated air through the sheet.

6. The improved method of drying paper in the course of manufacture in acontinuous sheet which comprises carrying the wet sheet between heatedfelts while successively forcing large volumes of heated air through thesheet, and further drying the sheet by alternately heating it andforcing large volumes of heated air therethrough and then bysuccessively forcing large volumes of heated air therethrough.

'7. The improved method of drying paper in the course of manufacture ina continuous sheet which comprises carrying the wet sheet between heatedfelts while alternately heating and forcing large volumes of heated airthrough the felts and interposed sheet, continuing the drying by heatingthe sheet and successively forcing large volumes of heated airtherethrough, and completing the drying by successively forcing largevolumes of heated air through the sheet.

8. A paper making machine comprising awet section on which the papersheet is made in the wet state, a press remote from the wet section,drying equipment through which the sheet is passed between said wetsection and press, said drying equipment comprising a series of suctiondrying rolls and heated drying rolls in alternation with suction dryingrolls, around which rolls successively the sheet is carried, and dryingequipment beyond said press comprising a series of suction drying rollsand heated drying rolls in alternation with suction drying rolls, aroundp 2,091,805 arranged to receive the wet sheet, said drying sectioncomprising a series of alternately arranged suction drying rolls andheated drying rolls and coacting endless aprons of porous materialbetween which the sheet is carried successively around said driers, asecond drying section comprising a series of alternately arrangedsuction drying rolls and heated drying rolls around which the sheet issuccessively carried 10 and an endless apron of porous material whichpasses with the sheet successively around said rolls of said secondsection, said apron being outside the sheet on heated drying rollsandinside the sheet on suction drying rolls, and a third drying sectioncomprising a series of driers ineluding heated drying rolls and suctiondrying rolls around which successively the sheet is carried.

HARRY A. CHUSE.

